District councilor Andrew Chiu receives medical treatment in Hong Kong, on Sunday, Nov. 3, 2019. Riot police stormed several malls in Hong Kong on Sunday in a move to thwart more pro-democracy protests, though violence did break out when a knife-wielding man slashed several people and bit off part of the ear of a local pro-democracy politician. (Elson Li/AP)

Witnesses said the attacker was subdued by passersby who beat him until the police arrived and arrested him.

The scene was especially chaotic since riot police were storming the mall trying to wrangle protesters who had chanted and broken shop windows, according to a BBC report.

Hong Kong has been the site of occasionally violent clashes between protesters that began over an extradition-to-China law which has morphed into a larger conflict over how the autonomous island is administered by the Chinese government.

During protests outside the mall on Sunday, police fired tear gas to disperse crowds of demonstrators.

The Chinese government had hinted that changes to how Hong Kong was administrated would be made but has not elaborated on its plans.